§9 acceptance: grep-zero sweep — every internal x.ai/grok identifier renamed

The PRD's first acceptance gate now holds: grep -RinE '\bx\.ai\b|grok'
crates/ --include='*.rs' → 0 matches (exempt: NOTICE and third-party
license archives, README provenance, and the required 'Based on Grok
Build Open Source' attribution, now sourced from version_attribution.txt).

Wire-visible renames (both sides in this repo, changed in lockstep):
- Auth method id 'grok.com' → 'kimi-code' (AuthMethodKind::KimiCode).
- Every x.ai/* and _x.ai/* ACP ext method and meta key → kigi/* /
  _kigi/* (~200 names; grokShell → kigiShell). Session-file replay keeps
  a read-side alias for the legacy '_x.ai/session/update' method so
  existing updates.jsonl histories load; writes emit only the new name
  (both directions test-pinned).
- Agent types grok-build* → kigi* with a documented legacy-prefix alias
  at resolution time so persisted sessions keep resolving.
- ToolNamespace/BuiltinAgentName GrokBuild* → Kigi* (wire snake_case
  kigi/kigi_concise/kigi_hashline; schema regenerated); grok_build
  implementation dirs renamed to kigi*.
- x-grok-* headers → x-kigi-*, __GROK_* sentinels → __KIGI_*, themes
  grokday/groknight → kigiday/kiginight (old persisted values fall back
  to the default theme), web_fetch allowlist xAI hosts → kimi.com +
  moonshot platforms, changelog CDN → this repo, grok-build changelog
  archives deleted.
- BYOK default endpoint removed: [endpoints] api_base_url is now truly
  optional with NO default — consumers fail fast with the flag name when
  unset (no silent x.ai egress). Mock harnesses inject it explicitly.
- System-prompt identity fixed: 'released by xAI' → 'an unofficial
  community CLI for Kimi' (template + regenerated encrypted form).

Also repaired pre-existing grok-era test debt found by the sweep: the
stale trace_classify default-model pin, the grok-pager UA label test,
pty-harness stale-binary reuse and non-hermetic moonshot routing (a PTY
test could previously reach the real api.moonshot.cn), and the outdated
oauth fixture scope key.

Gates: §9 grep 0; fmt clean; workspace check/clippy 0/0 (-D warnings);
FULL cargo test --workspace: 234 suites, 21,961 passed, 0 failed;
deny advisories ok.

crates/codegen/kigi-config/src/validation.rs

@@ -261,7 +261,7 @@ mod tests {
     fn load_requirements_layer_soft_fails_on_invalid_version_overrides() {
         use std::io::Write;
 
-        let dir = std::env::temp_dir().join(format!("grok-vo-soft-{}", std::process::id()));
+        let dir = std::env::temp_dir().join(format!("kigi-vo-soft-{}", std::process::id()));
         std::fs::create_dir_all(&dir).unwrap();
         let path = dir.join("requirements.toml");
         let mut f = std::fs::File::create(&path).unwrap();
@@ -285,7 +285,7 @@ telemetry = true
     fn validate_requirements_layer_errs_on_fail_closed_violation() {
         use std::io::Write;
 
-        let dir = std::env::temp_dir().join(format!("grok-vo-validate-{}", std::process::id()));
+        let dir = std::env::temp_dir().join(format!("kigi-vo-validate-{}", std::process::id()));
         std::fs::create_dir_all(&dir).unwrap();
         let path = dir.join("requirements.toml");
         let mut f = std::fs::File::create(&path).unwrap();
@@ -311,7 +311,7 @@ minimum_version = "not-a-version"
     fn validate_requirements_layer_ok_without_fail_closed() {
         use std::io::Write;
 
-        let dir = std::env::temp_dir().join(format!("grok-vo-soft2-{}", std::process::id()));
+        let dir = std::env::temp_dir().join(format!("kigi-vo-soft2-{}", std::process::id()));
         std::fs::create_dir_all(&dir).unwrap();
         let path = dir.join("requirements.toml");
         let mut f = std::fs::File::create(&path).unwrap();
@@ -377,7 +377,7 @@ minimum_version = "not-a-version"
     fn fail_closed_key_is_stripped_from_returned_layer() {
         use std::io::Write;
 
-        let dir = std::env::temp_dir().join(format!("grok-vo-strip-{}", std::process::id()));
+        let dir = std::env::temp_dir().join(format!("kigi-vo-strip-{}", std::process::id()));
         std::fs::create_dir_all(&dir).unwrap();
         let path = dir.join("requirements.toml");
         let mut f = std::fs::File::create(&path).unwrap();
@@ -403,7 +403,7 @@ minimum_version = "not-a-version"
     fn load_user_requirements_reads_layer_when_home_present() {
         use std::io::Write;
 
-        let dir = std::env::temp_dir().join(format!("grok-req-load-{}", std::process::id()));
+        let dir = std::env::temp_dir().join(format!("kigi-req-load-{}", std::process::id()));
         std::fs::create_dir_all(&dir).unwrap();
         let mut f = std::fs::File::create(dir.join("requirements.toml")).unwrap();
         writeln!(f, "[features]\ntelemetry = true\n").unwrap();
@@ -423,7 +423,7 @@ minimum_version = "not-a-version"
     fn validate_user_requirements_errs_on_fail_closed_violation() {
         use std::io::Write;
 
-        let dir = std::env::temp_dir().join(format!("grok-req-validate-{}", std::process::id()));
+        let dir = std::env::temp_dir().join(format!("kigi-req-validate-{}", std::process::id()));
         std::fs::create_dir_all(&dir).unwrap();
         let mut f = std::fs::File::create(dir.join("requirements.toml")).unwrap();
         writeln!(